It's not possible with the released versions (v14 and below) as the MAC address of the emulated NIC is hardcoded. So basically if you ran two instances, you'd have a MAC address conflict which means the two clients wouldn't be able to communicate.

There's a patch for it so you'd have to compile from source, and theoretically it'd be possible. I may try, as I'd like to set up and play with fun things like OS/2, Netware, BOOTP clients, all that good stuff.